media/audio/fake_audio_input_stream.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "media/audio/fake_audio_input_stream.h"
   6
   7 #include "base/bind.h"
   8 #include "base/lazy_instance.h"
   9 #include "media/audio/audio_manager_base.h"
  10
  11 using base::TimeTicks;
  12 using base::TimeDelta;
  13
  14 namespace media {
  15
  16 namespace {
  17
  18 // These values are based on experiments for local-to-local
  19 // PeerConnection to demonstrate audio/video synchronization.
  20 const int kBeepDurationMilliseconds = 20;
  21 const int kBeepFrequency = 400;
  22
  23 // Intervals between two automatic beeps.
  24 const int kAutomaticBeepIntervalInMs = 500;
  25
  26 // Automatic beep will be triggered every |kAutomaticBeepIntervalInMs| unless
  27 // users explicitly call BeepOnce(), which will disable the automatic beep.
  28 struct BeepContext {
  29   BeepContext() : beep_once(false), automatic(true) {}
  30   base::Lock beep_lock;
  31   bool beep_once;
  32   bool automatic;
  33 };
  34
  35 static base::LazyInstance<BeepContext> g_beep_context =
  36     LAZY_INSTANCE_INITIALIZER;
  37
  38 }  // namespace
  39
  40 AudioInputStream* FakeAudioInputStream::MakeFakeStream(
  41     AudioManagerBase* manager,
  42     const AudioParameters& params) {
  43   return new FakeAudioInputStream(manager, params);
  44 }
  45
  46 FakeAudioInputStream::FakeAudioInputStream(AudioManagerBase* manager,
  47                                            const AudioParameters& params)
  48     : audio_manager_(manager),
  49       callback_(NULL),
  50       buffer_size_((params.channels() * params.bits_per_sample() *
  51                     params.frames_per_buffer()) / 8),
  52       params_(params),
  53       thread_("FakeAudioRecordingThread"),
  54       callback_interval_(base::TimeDelta::FromMilliseconds(
  55           (params.frames_per_buffer() * 1000) / params.sample_rate())),
  56       beep_duration_in_buffers_(
  57           kBeepDurationMilliseconds * params.sample_rate() /
  58           params.frames_per_buffer() / 1000),
  59       beep_generated_in_buffers_(0),
  60       beep_period_in_frames_(params.sample_rate() / kBeepFrequency),
  61       frames_elapsed_(0) {
  62 }
  63
  64 FakeAudioInputStream::~FakeAudioInputStream() {}
  65
  66 bool FakeAudioInputStream::Open() {
  67   buffer_.reset(new uint8[buffer_size_]);
  68   memset(buffer_.get(), 0, buffer_size_);
  69   return true;
  70 }
  71
  72 void FakeAudioInputStream::Start(AudioInputCallback* callback)  {
  73   DCHECK(!thread_.IsRunning());
  74   DCHECK(!callback_);
  75   callback_ = callback;
  76   last_callback_time_ = TimeTicks::Now();
  77   thread_.Start();
  78   thread_.message_loop()->PostDelayedTask(
  79       FROM_HERE,
  80       base::Bind(&FakeAudioInputStream::DoCallback, base::Unretained(this)),
  81       callback_interval_);
  82 }
  83
  84 void FakeAudioInputStream::DoCallback() {
  85   DCHECK(callback_);
  86
  87   const TimeTicks now = TimeTicks::Now();
  88   base::TimeDelta next_callback_time =
  89       last_callback_time_ + callback_interval_ * 2 - now;
  90
  91   // If we are falling behind, try to catch up as much as we can in the next
  92   // callback.
  93   if (next_callback_time < base::TimeDelta())
  94     next_callback_time = base::TimeDelta();
  95
  96   // Accumulate the time from the last beep.
  97   interval_from_last_beep_ += now - last_callback_time_;
  98
  99   last_callback_time_ = now;
 100
 101   memset(buffer_.get(), 0, buffer_size_);
 102
 103   bool should_beep = false;
 104   {
 105     BeepContext* beep_context = g_beep_context.Pointer();
 106     base::AutoLock auto_lock(beep_context->beep_lock);
 107     if (beep_context->automatic) {
 108       base::TimeDelta delta = interval_from_last_beep_ -
 109           TimeDelta::FromMilliseconds(kAutomaticBeepIntervalInMs);
 110       if (delta > base::TimeDelta()) {
 111         should_beep = true;
 112         interval_from_last_beep_ = delta;
 113       }
 114     } else {
 115       should_beep = beep_context->beep_once;
 116       beep_context->beep_once = false;
 117     }
 118   }
 119
 120   // If this object was instructed to generate a beep or has started to
 121   // generate a beep sound.
 122   if (should_beep || beep_generated_in_buffers_) {
 123     // Compute the number of frames to output high value. Then compute the
 124     // number of bytes based on channels and bits per channel.
 125     int high_frames = beep_period_in_frames_ / 2;
 126     int high_bytes = high_frames * params_.bits_per_sample() *
 127         params_.channels() / 8;
 128
 129     // Separate high and low with the same number of bytes to generate a
 130     // square wave.
 131     int position = 0;
 132     while (position + high_bytes <= buffer_size_) {
 133       // Write high values first.
 134       memset(buffer_.get() + position, 128, high_bytes);
 135       // Then leave low values in the buffer with |high_bytes|.
 136       position += high_bytes * 2;
 137     }
 138
 139     ++beep_generated_in_buffers_;
 140     if (beep_generated_in_buffers_ >= beep_duration_in_buffers_)
 141       beep_generated_in_buffers_ = 0;
 142   }
 143
 144   callback_->OnData(this, buffer_.get(), buffer_size_, buffer_size_, 1.0);
 145   frames_elapsed_ += params_.frames_per_buffer();
 146
 147   thread_.message_loop()->PostDelayedTask(
 148       FROM_HERE,
 149       base::Bind(&FakeAudioInputStream::DoCallback, base::Unretained(this)),
 150       next_callback_time);
 151 }
 152
 153 void FakeAudioInputStream::Stop() {
 154   thread_.Stop();
 155   callback_ = NULL;
 156 }
 157
 158 void FakeAudioInputStream::Close() {
 159   audio_manager_->ReleaseInputStream(this);
 160 }
 161
 162 double FakeAudioInputStream::GetMaxVolume() {
 163   return 1.0;
 164 }
 165
 166 void FakeAudioInputStream::SetVolume(double volume) {
 167 }
 168
 169 double FakeAudioInputStream::GetVolume() {
 170   return 1.0;
 171 }
 172
 173 void FakeAudioInputStream::SetAutomaticGainControl(bool enabled) {}
 174
 175 bool FakeAudioInputStream::GetAutomaticGainControl() {
 176   return true;
 177 }
 178
 179 // static
 180 void FakeAudioInputStream::BeepOnce() {
 181   BeepContext* beep_context = g_beep_context.Pointer();
 182   base::AutoLock auto_lock(beep_context->beep_lock);
 183   beep_context->beep_once = true;
 184   beep_context->automatic = false;
 185 }
 186
 187 }  // namespace media